Periodic Reporting for period 3 - SPAWN (Simulating particle acceleration within black hole magnetospheres)
Période du rapport: 2023-09-01 au 2025-02-28
Black holes are often referred as the simplest objects in the Universe because they are fully characterized by their mass, their electric charge and their spin. In comparison, describing the properties of a planet for instance would be a much more tedious task (e.g. chemical composition, internal structure, atmosphere, magnetic field, temperature, etc…). Thus, in spite of the complex mathematical framework of general relativity that is needed to describe them, black holes as such are simple well-defined bodies. Their role as the main engine powering some of the most violent and energetic events in the Universe has been suspected for many years. Thanks to the discovery of gravitational waves emitted by merging stellar-mass black holes and the imaging of the nearby supermassive black holes M87* and SgrA*, we now have direct evidence of their existence.
Although black holes swallow anything that comes to reach of their irresistible gravitational field, their appetite for accreting matter does not proceed unnoticed. The surrounding gas is heated up to extreme temperatures as it approaches the black hole event horizon, leading to a complete dissociation of atoms into a soup of electrons and ions called a “plasma”. This plasma is a bright source of light that is then received and analyzed on Earth. Hence, this emitted light encodes crucial information on how matter behaves under these extreme physical conditions. The main goal of this project is to model the dynamic of a plasma and the light it emits near a black hole to decipher current and future observations at the scale of black hole horizon. To this end, we use state-of-the-art numerical simulations to produce virtual experiments on supercomputers of a spinning black hole immersed in a magnetized plasma. Our work focuses on the structure of a magnetosphere forming around black holes with an emphasis on the rearrangement of the magnetic field and its consequences on particle acceleration.
Although black holes swallow anything that comes to reach of their irresistible gravitational field, their appetite for accreting matter does not proceed unnoticed. The surrounding gas is heated up to extreme temperatures as it approaches the black hole event horizon, leading to a complete dissociation of atoms into a soup of electrons and ions called a “plasma”. This plasma is a bright source of light that is then received and analyzed on Earth. Hence, this emitted light encodes crucial information on how matter behaves under these extreme physical conditions. The main goal of this project is to model the dynamic of a plasma and the light it emits near a black hole to decipher current and future observations at the scale of black hole horizon. To this end, we use state-of-the-art numerical simulations to produce virtual experiments on supercomputers of a spinning black hole immersed in a magnetized plasma. Our work focuses on the structure of a magnetosphere forming around black holes with an emphasis on the rearrangement of the magnetic field and its consequences on particle acceleration.
Our main efforts during this mid-term reporting period have focused on building the most ab-initio model of an isolated black hole magnetosphere and a black hole connected to a Keplerian magnetized disk. We have firmly established the robustness of black-hole spin energy extraction in the form of a strong plasma jet. Similarly to their analog in the Solar System, black hole magnetospheres are highly dynamical. The sudden rearrangement of magnetic field lines or “reconnection” leads to an efficient acceleration of particles and a bright emission of light observable from Earth.
In parallel to these efforts, we are developing an innovative numerical framework designed to incorporate two complementary plasma models in the same code to improve the predictive power of our simulations. In the second half of the project, we will focus our attention on the modeling of a magnetized neutron star orbiting a spinning black hole with the aim to uncover a possible electromagnetic emission prior to the merging of both stars and in coincidence with the emission of gravitational waves.